Ataxia-telangiectasia syndrome is an autosomal recessive associated with combined immunodeficiency, progressive cerebellum ataxia, telangiectasia, ocolomotor apraxia, dysartheria and respiratory infections. In this study we reported three cases from a family with classical symptoms. Second sibling was died at 13 old years because severe respiratory infection but third and forth siblings have life. The first sibling is female and normal.